This invention relates to a mechanical movement to translate rotational to linear motion and, more particularly, to an inexpensive leadscrew linear-movement assembly.
Electric motors commonly produce a rotational output, but many mechanisms require a linear movement driven by the motor. A leadscrew assembly is one approach for translating the rotational movement of the motor to the required linear movement. In the conventional leadscrew assembly, the thread of an externally threaded leadscrew engages a recirculating ball nut structure, which in turn is engaged to the structure to be driven linearly. As the leadscrew turns, the ball nut structure and the driven structure move linearly.
This conventional leadscrew assembly is relatively expensive to produce due to the precision machining required. It is also limited to relatively large-size devices and coarse thread pitches because of the size of the balls used in the recirculating ball nut structure. The conventional leadscrew assembly may also be subject to excessive wear of the threads, particularly if there is any misalignment.
An advance in overcoming these disadvantages is described in U.S. Pat. No. 5,636,549, whose disclosure is incorporated by reference. The '549 patent discloses a leadscrew in which the thread structure is defined by a wire wound helically around a cylindrical form. A leadscrew-nut assembly is also disclosed for engaging the leadscrew to the linear slide assembly.
The approach of the '549 patent is operable for many applications but is not optimal for other applications such as those requiring light duty, low loads, and low speeds of operation. There is a need for realizing the advantages of the basic approach disclosed in the '549 patent, but in a form more suitable to these other applications. The present invention fulfills this need, and further provides related advantages.